As the method for processing the surface of a sample by irradiating the surface of the sample with a gas cluster, for example there is a method using a gas cluster ion beam, which removes atoms and molecules on the surface of a sample by causing a gas cluster to be ionized, and accelerated with an electrical field and/or a magnetic field to collide with the surface of the sample (for example, see Patent Document 1).
In the above-described method for processing the surface of a sample, a gas cluster composed of an aggregated atom or molecular group of a gaseous substance is formed by jetting out from a gas supplying unit a pressurized mixed gas of a substance, which is in a gaseous state at normal temperatures and under normal pressures, and a rare gas. Then, the gas cluster is ionized by irradiating the gas cluster with an electron beam, and thereby a gas cluster ion beam is formed.
If a solid surface is irradiated with this gas cluster ion beam, multiple-step collision occurs between molecular or atom species constituting cluster ions, and between the molecular or atom species constituting cluster ions and the atoms on the solid surface. Because of this, reflected atoms or molecules having lateral motion components are generated, and with these reflected atoms or molecules, flattening and cleaning of a substrate surface are enabled.
Thus, it is possible to process the surface of a sample with a gas cluster ion beam.
Also, it is proposed to provide a processing apparatus using cluster ions with i) an accelerating electrical field unit for giving acceleration voltage to cluster ions and ii) a decelerating electrical field unit for giving deceleration voltage to cluster ions, and decrease acceleration voltage to be given to cluster ions in a stepwise or continuous manner (for example, refer to Patent Document 2).
Patent Document 1: Japanese Unexamined Patent Application Publication No. H8-319105
Patent Document 2: Japanese Unexamined Patent Application Publication No. 2005-310977